Gunsmithing Bore diameter for muzzle break?

[KQguy]

I bought a 3 port muzzle break from a guy that machined it out for me.I told him I shoot a 7mm,so when I got the break,I measured the bore diameter,it measure exactly .284".Is this too tight,or is it ok to use it like that?

 

[JJones75]

Re: Bore diameter for muzzle break?

Thats way to tight , if the threads were cut at the some time the bore was cut and the bore was predrilled then machined to ensure that its strait then the brake can be reamed .020" over bullet diameter , thats as tight as I would go , personaly I'd just ream it with a 5/16 that would make about .030" over bullet diameter.

You must also make sure that the htread cut on the mussle were cut while the barrle was indicated off the bore and not the od

 

[mscott]

Re: Bore diameter for muzzle break?

The exit hole of my 7mm JP brake is .310. The first baffle hole is a little larger than that, but I can't accurately measure it.

 

[jrpilot]

Re: Bore diameter for muzzle break?

.020-.030 larger than bullet Dia.

 

[KQguy]

Re: Bore diameter for muzzle break?

Thanks for the input,I will get it drilled out bigger when it gets installed.

 

[kingjoey]

Re: Bore diameter for muzzle break?

Sounds like the guy shouldn't be making muzzlebrakes